The present invention relates generally to medical instruments and more particularly to a disposable syringe having a retractable needle. More specifically this invention relates to a syringe which, during fluid injection or displacement of the contents from the syringe, a vacuum is created within the syringe body to automatically retract the needle into the inside of the syringe body after syringe use, to prevent accidental needlesticks.
Health care workers routinely risk exposure to communicable diseases through accidental exposure to contaminated medical products, waste products and bodily fluids. One of the largest exposure risks to healthcare workers and handlers of related hazardous waste is from accidental needlesticks or scratches while using hypodermic syringes. The Centers for Disease Control and Prevention reports that there are in excess of one-half million reported accidental needlesticks each year and an estimated three million additional needlesticks not reported. It is further reported that the odds of a healthcare worker contracting human immunodeficiency virus (HIV) alone through a needlestick are one in 300. The odds of a healthcare worker contracting any of many other serious or potentially fatal diseases such as hepatitis are even greater. In response to this health issue some states and the federal government are enacting legislation requiring exclusive use of safety hypodermic syringes with retractable or protected needles, e.g., the federal Needlestick Safety and Prevention Act.
Numerous solutions to the needlestick problem have been proposed, including U.S. Pat. No. 4,790,822, which discloses a disposable syringe in which the needle can be captured by a plunger and then fully retracted into the barrel of the syringe. The plunger shaft may then be broken off flush with the end of the barrel such that the needle may not be mechanically projected to extend beyond the opposite end of the barrel.
U.S. Pat. No. 4,747,830 discloses a similar system including a plunger that can be broken off once the needle is fully retracted into the barrel of the plunger. U.S. Pat. Nos. 4,692,156 and 4,675,005 both disclose disposable syringes wherein the needle can be fully retracted into the barrel of the plunger. U.S. Pat. No. 4,643,200 discloses a similar system used with a blood donor assembly, which allows retraction of a needle into a barrel.
U.S. Pat. No. 4,425,120 discloses a movable needle guard conduit which extends from the barrel of the syringe over the full length of the needle. The needle guard may be retracted during use of the syringe and may then re-extend to cover the needle following use of the syringe. U.S. Pat. No. 4,816,022 discloses a syringe with a sliding cap which utilizes a nub and backseat for engagement of a nosepiece for securing the cap around the syringe. U.S. Pat. No. 3,008,570 discloses a removable cap for enclosing and protecting a sterilized syringe in a moveable housing.
U.S. Pat. No. 5,000,736 discloses a syringe including a tubular plunger from which air has been evacuated which upon use may retract the needle into the plunger by differential pressure. U.S. Pat. No. 5,885,257 discloses a syringe which utilizes a compressed spring placed between a needle carrier and the barrel of the syringe and including a releasable retaining means to hold the needle carrier in position until retraction is desired. U.S. Pat. No. 4,908,022 discloses a disposable safety syringe including a cylinder which is pre-filled with fluid medication, a double ended needle and a plunger. Following use of the syringe, the end of the needle which extends into the barrel may penetrate the piston such that the needle may be manually withdrawn into the barrel by axial retraction of the plunger which remains in engagement with the needle.
Thus, a variety of prior art retractable syringes are known. Prior art syringes, however, have not offered a universally acceptable solution to the needlestick issue. Healthcare workers throughout the world may benefit from a syringe which reduces or eliminates the risk of accidental needlestick or exposure to contaminated surfaces such as the exterior surface of a used needle, by overcoming the disadvantages of prior art syringes. An improved syringe is desired which is simple in design, manufacturing and operation so as to be widely applicable, cost effective, reliable and which does not require pre-filling with medication or fabricating with stored potential energy. A syringe is also desired which may become an industry standard through overcoming the disadvantages of prior art.
The disadvantages of the prior art are overcome by the present invention and an improved retractable needle syringe is hereinafter disclosed which has particular utility in protecting healthcare and sanitation workers.
The present invention is a hypodermic syringe apparatus (syringe) that may retract a hypodermic needle into a syringe body after the syringe contents have been discharged, so as to prevent accidental needlesticks, scratches or other exposure to healthcare workers of contaminated needles or fluids thereon. In addition to protecting healthcare workers, this invention may also prevent the multiple use or sharing of syringes and needles. This invention may also protect workers involved with disposal and sanitation of used syringes and may reduce the likelihood of infectious particulates becoming airborne. The syringe may preferably be a disposable, single use type and may be available in various standard and non-standard sizes and shapes.
It is an object of the present invention to provide an improved vacuum operated, retractable-needle syringe. A preferred embodiment of this invention may include: (a) a selectively retractable needle assembly including a hypodermic needle and needle seat apparatus for supporting and engaging the hypodermic needle; (b) a cylindrical syringe body to provide each of a reservoir for injectable or withdrawn fluids and a vacuum chamber; (c) a piston assembly to create pressure differentials within the cylinder body to draw fluids into the syringe body or discharge fluids contained within the syringe body, and to assist in producing a vacuum; (d) a hollow shaft and press plate for manipulation of the piston assembly; (e) a top seal for engaging and sealing with both the cylinder body and shaft to provide a pneumatic annular chamber within the cylinder body to retract the needle assembly, and (f) a valve assembly ton regulate air movement into and from within the annular chamber. All seals referenced herein are pneumatic and/or hydraulic seals.
The needle assembly may be selectively retractable in that a connector on the needle assembly may be selectively connected with a connector on the piston assembly and the needle assembly selectively and automatically retracted into the cylinder body. While moving the piston assembly relative to the cylinder body, the practitioner may discharge fluid into the fluid receptacle. In addition, the discharging piston stroke may close a valve assembly and create a substantial vacuum or low-pressure region within the annular chamber, which may be used thereafter to automatically withdraw the needle into the cylinder body once the injection is complete.
It is an object of the present invention to provide a piston and valve operated mechanism for creating and maintaining potential energy within the syringe, during use of the syringe for retracting the needle assembly upon completion of syringe use.
It is also an object of this invention to selectively connect a piston assembly with a selectively disengageable needle assembly. When the fluid is substantially fully discharged, a connector secured to the piston assembly may engage a connector secured to the needle assembly. A slight increase in axial force upon the shaft may attach the shaft and/or the piston assembly to the needle assembly. After needle assembly retraction the hypodermic needle may be fully encased and protected within the syringe body.
It is a feature of the present invention that the retractable syringe is simple to operate and economical to manufacture.
It is another feature of this invention that the syringe may be operated substantially by one hand, as required by many regulatory and safety codes and statutes.
It is also a feature of the present invention that the syringe is highly reliable and may fully perform its intended purpose, to facilitate a hypodermic injection and then fully retract and retain the used hypodermic needle within the syringe cylinder body immediately upon completion of use.
A significant feature of the invention is that the practitioner may utilize a syringe according to this invention in substantially the same order of operations as a conventional disposable syringe which does not automatically retract the needle.
Although preferred embodiments are disclosed, other embodiments may naturally evolve from the concepts of this invention and as such remain within the scope of this invention. Several alternative embodiments are disclosed in the attached drawings and detailed specifications. The concepts of this invention may be applied to syringes for use in hypodermic injections and withdrawals, including blood donation apparatus and related medical and technical equipment employing a potentially penetrating or scratching hypodermic needle or puncturing device.
The disadvantages over prior art are overcome by the present invention, and an improved disposable safety syringe having a retractable needle and an improved method of operating a hypodermic syringe and capturing a hypodermic needle inside a syringe body is disclosed.